Island



T. s. cumls.v i EL'ECTRIC FURNACE.

I I APPLICATION FILED AusJ, 1919.. 1,433,448,

Patented Oct. 24,1922.

. g t Times Sh /67611753 attain;

Patented Oct. 24, 1922.

UNITED STATES 1,433,448 PATENT OFFICE.

THOMAS STANLEY CURTIS, OF PROVIDENCE, Eli-ODE ISLAND, ASSIGNOR TO UNIVERSAL OPTICAL CORPORATION, OF PROVIDENCE, RHODE ISLAND, A

CORPORATION OF RHODE ISLAND.

ELECTRIC FURNACE.

Application. filed August '6, 1919. Serial No. 315,972.

To all whom it may concem:

Be it known that I, THOMAS STANLEY Cums, a citizen of the United States, and

resident of the city of Providence, in the,

county of Providence and State of Rhode Island, have invented certain new and useful improvements in Electric Furnaces, of which the following is a specification.

This invention relates to a new method and apparatus for treating magnesite and other ores with electrically generated heat for the purpose primarily of producing a highly refractory material.

The object of this invention is to fuse the material into a dense mass or clinker having its maximum gravity or density.

A further objectof this invention 1s the provision of means whereby the heat-conducting electrodes may be gradually separated during the fusing process for the purpose of enlarging the volume through which the current must pass and so fuse the maximum amount of material during each operation.

A still further object of the invention is to so deposit the material about the electrodes that that portion adjacent the electrode will be fused and that portion surrounding the fused portion will be calcined or partially burned whereby when cooled the fused portion may be readily removed in one unbroken lump or mass from the calcined portion, and

' the calcined portion may be positioned about the electrodes to be fused in a subsequent operation.

With these and other objects in view, the invention consists of certain novel features as will be more fully described, and particularly pointed out in the appended claims.

In the accompanying drawings:

Figure 1 is a sectional side elevation of a furnace illustrating my improved method of treating" ore.

Figure 2 is an end elevation of the device illustrated in Figure 1.

Referring to the drawings, 10 designates a furnace which may be made in any suitable form but preferably in the present case it is made rectangular, the walls of which may be built up of brick or other suitable refratory material, the side walls 9 being preferably arranged so that they may be readily removed after each operation to facilitate the removal of the charge. The end walls 11 of the furnace are preferably provided with a hole 12 in which is slidably mounted horizontally-disposed electrodes 13 whose inner ends when first positioned are adapted to meet in the center of the furnace and whose outer ends 14- are each supported on a carriage 15, whereby they may be withdrawn and separated gradually, either intermittently or continuously as desired, during the treating of the charge in the furnace. Each of these carriages is shown as being movably mounted on wheels 16 to roll on rails 17, the latter being graduated so as to indicate the. exact distance each electrode has been withdrawn, and a suitable mechanism such as a crank 18 connected by a sprocket 19 to one of the wheel shafts may be provided if desired, to facilitate the movement of the carriage by the operator.

1n building up a charge in this furnace to be operated upon by my improved process, I first deposit a layer 20 of raw or untreated ore on the bottom of the furnace, piling the same up to some extent around the side and end walls for the purpose of protecting these Walls against the heat, I then osition the electrodes l3'so that their ends will abut, and then deposit in the middle of the furnace about the electrodes a quantity of previously calcined ore 21, or ore partially baked and freed from the greater portion of its carbon dioxide by having been subjected to a moderate degree of heat; I then pour in another layer 22 of raw material over and around this middle portion of calcined material.

by enlarging the volume of material through which the current is caused to pass to obtain ,the maximum amount of fused material in each charge. The current passing through the highly heated core of magnesite causes it to become a conductor of the current when hot, although this magnesite is an insulator when cold.

The outer layer or envelope of raw material serves a double wurpose; first, it incloses the inner mass oi fused material and 1 Assess prevents the heat from radiating to and destroying the inclosing Wells; second, this outer layer absorbs the heat which is conducted to it from the inner mess While foeing', which hes-t serves to calcine the outer portion and practically free the some from,

its contained carbon dioxide providing a partially beked meteriel Which will serve as a conducting core for the next succeeding charge.

Thus We have effected a. thorough fusion of the core by turning it into e resistor, the Withdrawing of the electrodes servingjmerely to set up condition of conductivity in suc- After this process hes been continued for e suiiieient length of time the current is turned off and the Whole allowed to cool.

in practice it hes heretofore been'iound' an expensive and dillicult operation to remove the fused or sintered portion of the charge from the calcined portiones this fused portion has never before been sup ported by as broken, unfused mess, but with my improved method of building the fur nace charge it is only necessary after scrap ing ewsy the loose, new celcined outer layer of materiel, to heel; onto this fused portion end'lift the some, by moons of grappling irons e crene, in an unbroken mess of substentielly egg shape from its bed of disintegrated, unfuscd materiel, with precti- Cally none of this unfused ore clinging to it,

The side walls cl the furnace may be removed ii desired to further facilitate the removal. of the furnace charge.

If this fused lump is now permitted to fell e distance it will be broken up ready for the crusher. The calcined or remeining por tion of the ore in the furnace, which formed the originel envelope for the fused portion is noW removed from the fiirnece ready-to be heated chsrge end. so-

placed in anothertcherge about the electrodes to complete its fusing in a subsequent opera tion.

lllsgnesite fusedby my improved method forms a refractory which has been shrunk and reduced to its maximum density and, therefore, will not further shrink and for this reason it is 'most valuable for use in the construction of materials designed to Withstend a high degreefof heat, such for instance as retorts, furnace linings, crucibles, muflles and for numerous other similar purposes.

Hevin thus described one illustrative em- I w I: I I 1 bodiment of my invention and the best mode lcno'wntome for cerr i ingout my method, I

desire it to be understood that although specific terms ore employed, they are used in e'generio and descriptive sense and not for the purposeof limitation, the scope of the invention. being defined and limited only by the terms of the eppended claims.

I claim;

.1. ln s furnace, horizontally disposed electrodes positioned end to end, a carrier for said electrodes whereby they may be separated-end a graduated scale by which the reletive positions of said carriers may be readily determined.

'2. .ln e furnace, electrodes projecting through the Walls into the furnace and positioned to be covered by the charge, as carrier in which the outer portion of said electrodes is mounted whereby said carrier may be moved to Withdraw seid electrodes through the charge during the fusing operation.

3. Iii-e furnace, horizontally disposed electrodes positioned end to end, each extending through the Wells into the furnace, a carrier for supporting the outer end of said electrodes means whereby said carriers may be moved to regulate the position of said electrodes relative to each other and a graduated member by which the relative position of said carriers may be readily deter mined, y

. In testimony whereoflsfiix my signature.

l l-l'illvlAS STANLEY CURTIS. 

